Certain heart defects require implantation of a conduit for blood flow to bypass valve aplasia or severe stenosis. These include but not limited to cases of a pulmonary artery only with no aorta. The added conduit may or may not include a valve. There are several types of conduits, including but not limited to:
Homograft—from the same species (i.e. another human)
Heterograft—from a different species (e.g. pig)
Artificial—man-made materials (e.g. Gortex)
Combination of two or more of the above.
In any case, the conduits may eventually become calcified and/or stenotic. Currently, cardiac catheterization, Doppler echocardiography, and/or Magnetic Resonance Imaging (MRI) are used to assess the degree of stenosis. Catheterization gives the best assessment, since it can directly measure the pressure gradient across the conduit; however, it carries progressive morbidity and mortality. Furthermore, all three methods require specialized equipment and they provide only a snapshot of the physiologic status.
Occlusion is an eventuality in nearly all conduit cases; the question is only a matter of when it will occur. The impact of occlusion includes right ventricle (RV) failure. Treatment for occlusion is to replace the conduit entirely. Physicians need a means of noninvasively, accurately monitoring conduit condition on a continuous basis in order to determine whether and when conduit revision is required. Furthermore, remote monitoring of conduit condition would simultaneously reduce the number of hospital and clinic visits while increasing the overall timeliness of treatment.